media-video/ffmpeg-4.4.2::gentoo was built with the following:
USE="X alsa bzip2 dav1d encode gnutls gpl iconv libdrm mp3 network openh264 opus pic postproc svg threads vaapi vdpau vulkan x264 zlib (-amf) -amr -amrenc (-appkit) -bluray -bs2b -cdio -chromaprint -chromium -codec2 -cpudetection (-cuda) -debug -doc -fdk -flite -fontconfig -frei0r -fribidi -gcrypt -gme -gmp -gsm -hardcoded-tables -iec61883 -ieee1394 -jack -jpeg2k -kvazaar -ladspa -libaom -libaribb24 -libass -libcaca -libilbc -librtmp -libsoxr -libtesseract -libv4l -libxml2 -lv2 -lzma (-mipsdspr1) (-mipsdspr2) (-mipsfpu) (-mmal) -modplug -nvenc -openal -opencl -opengl -openssl -oss -pulseaudio -rav1e -rubberband -samba -sdl -snappy -sndio -speex -srt -ssh -static-libs -svt-av1 -test -theora -truetype -twolame -v4l -verify-sig -vidstab (-vmaf) -vorbis -vpx -webp -x265 -xvid -zeromq -zimg -zvbi" ABI_X86="32 (64) (-x32)" CPU_FLAGS_X86="aes avx avx2 fma3 mmx mmxext sse sse2 sse3 sse4_1 sse4_2 ssse3 -3dnow -3dnowext -fma4 -xop" FFTOOLS="aviocat cws2fws ffescape ffeval ffhash fourcc2pixfmt graph2dot ismindex pktdumper qt-faststart sidxindex trasher"
FEATURES="binpkg-logs usersync pid-sandbox xattr preserve-libs qa-unresolved-soname-deps sfperms metadata-transfer strict ebuild-locks sandbox usersandbox fixlafiles userpriv merge-sync unmerge-orphans multilib-strict config-protect-if-modified parallel-install network-sandbox parallel-fetch ipc-sandbox assume-digests binpkg-multi-instance buildpkg-live unknown-features-warn protect-owned news userfetch binpkg-dostrip unmerge-logs candy distlocks binpkg-docompress"